BACKGROUND
1. Technical Field
[0001] The present invention relates to a fluid discharging apparatus and a method of discharging
a fluid.
2. Related Art
[0002] Various fluid discharging apparatuses that discharge a fluid from a discharge port
are proposed. For example,
JP-A-2002-282740 discloses a liquid droplet discharging apparatus in which a plunger rod is caused
to perform reciprocation in a liquid chamber as an accommodation unit, and thus a
liquid is discharged in a form of droplets by extruding the liquid from a discharge
port. A discharging mechanism of a fluid, which uses a moving object such a plunger
rod in
JP-A-2002-282740 may be applied to, for example, an ink jet printer that produces a printout by discharging
an ink, or a 3D printer that models a three-dimensional object by discharging a liquid
material.
[0003] In the above-described fluid discharging apparatus, a situation in which, after a
fluid is discharged, the next fluid is hindered from being discharged by the fluid
which has adhered to a circumference of a discharge port may occur. In the fluid discharging
apparatus, a technique of suppressing a fluid from remaining on the circumference
of the discharge port after the fluid is discharged may be improved more.
[0004] US 2009/167818 A1 discloses a highly viscous fluid discharging apparatus which includes: a nozzle including
a discharge opening having a predetermined inner volume, and a widened portion formed
at a position immediately before the discharge opening and expanding from the discharge
opening. A plunger is supplied which is capable of opening and closing the discharge
opening by causing the leading-end portion of the plunger to move away from and to
move towards the widened portion. A driver is also provided which is configured to
move the plunger in a direction of closing the discharge opening against a biasing
force that biases the plunger in a direction of opening the discharge opening. During
a stand-by period, the discharge opening is kept closed by an action of the plunger
that is caused by the driver to press the leading-end portion onto the widened portion.
[0005] US 2014/346253 A1 discloses a droplet forming device for discharging a droplet in a flying fashion
from a nozzle, the device including a liquid chamber that is communicated with the
nozzle and is supplied with a liquid material, a plunger rod having a tip that is
moved to advance and retreat within the liquid chamber, a spring that applies a biasing
force to the plunger rod, a pressurization chamber that is supplied with a pressurized
gas acting to retreat the plunger rod, a pressure source that supplies the pressurized
gas to the pressurization chamber, and a controller. The droplet forming device further
includes a magnetic field generating mechanism that generates an attraction force
to act in an advancing direction when the plunger rod approaches a most advanced position
thereof.
SUMMARY
[0006] The invention can be realized as the following aspects.
According to a first aspect of the invention, there is provided a fluid discharging
apparatus according to claim 1.
[0007] According to the fluid discharging apparatus in this aspect, it is possible to suppress
an occurrence of a situation in which an outside air is entered into the accommodation
unit through the discharge port in the moving processing.
[0008] According to the fluid discharging apparatus in the above aspect, the moving object
is moved in a direction away from the discharge port during a period when the fluid
is discharged from the discharge port, and thus a force which acts in a direction
in which the fluid is drawn back from the discharge port into the accommodation unit
can be generated. With the generated force, it is possible to separate a fluid droplet
which is required to be scattered toward a target from a fluid which has been extruded
from the discharge port, and to bring the remaining fluid back into the accommodation
unit. Thus, an occurrence of a situation in which a redundant fluid is provided is
at a circumferential portion of the discharge port after the fluid is discharged is
effectively suppressed.
[0009] In the fluid discharging apparatus of this aspect, the control unit may move the
moving object in the first direction so as to reach the closed position after moving
the moving object in the second direction in the discharging processing.
[0010] According to the fluid discharging apparatus in this aspect, it is possible to increase
a force which is generated after the discharging processing and acts in a direction
in which the fluid is drawn back from the discharge port into the accommodation unit.
Accordingly, an occurrence of a situation in which a redundant fluid is provided is
at the circumferential portion of the discharge port is further suppressed.
[0011] In the fluid discharging apparatus of this aspect, a distance when the moving object
moves in the second direction in the moving processing may be equal to or smaller
than a distance when the moving object moves in the second direction in the discharging
processing. According to the fluid discharging apparatus in this aspect, an occurrence
of a situation in which the moving object is excessively moved is suppressed.
[0012] In the fluid discharging apparatus of this aspect, the control unit may bring the
moving object back to the closed position, at a speed which is slower than a moving
speed when the control unit moves the moving object in the first direction in the
discharging processing, after the step of moving moving object in the first direction
in the discharging processing.
[0013] According to the fluid discharging apparatus in this aspect, an occurrence of a situation
in which a redundant fluid is extruded outwardly from the discharge port when the
discharge port is closed in the moving processing is suppressed.
[0014] According to a second aspect of the invention, there is provided a method of discharging
a fluid according to claim 5.
[0015] According to the method, an occurrence of a situation in which a redundant fluid
is provided is in the circumference of the discharge port after the fluid is discharged
is effectively suppressed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] The invention will be described with reference to the accompanying drawings, wherein
like numbers reference like elements.
Fig. 1 is a schematic diagram illustrating a configuration of a fluid discharging
apparatus in a first reference example.
Fig. 2 is a flowchart illustrating a flow of a discharging process of a fluid.
Fig. 3 is a diagram illustrating a relationship between a position of a moving object
and a time in the discharging process.
Fig. 4A is a schematic diagram illustrating details of Process 1 in discharging processing.
Fig. 4B is a schematic diagram illustrating details of Process 2 in the discharging
processing.
Fig. 5A is a schematic diagram illustrating details of Process 3 in moving processing.
Fig. 5B is a schematic diagram illustrating details of Process 4 in the moving processing.
Fig. 6 is a diagram illustrating a discharging process in a second reference example.
Fig. 7 is a diagram illustrating a discharging process in a third exemplary embodiment.
Fig. 8 is a schematic diagram illustrating a configuration of a fluid discharging
apparatus in a fourth reference example.
DESCRIPTION
A. First Reference Example
[0017] Fig. 1 is a schematic diagram illustrating a configuration of a fluid discharging
apparatus 100 in a first reference example of the invention. Fig. 1 illustrates an
arrow G which indicates a gravity direction (vertical direction) when the fluid discharging
apparatus 100 is disposed in a general use state. In this specification, a direction
described as "up" or "down" means a direction using the vertical direction as a reference,
so long as particular statements are not made. Fig. 1 illustrates arrows which indicate,
respectively, a first direction D1 and a second direction D2 which will be described
later. The arrows G, D1, and D2 are appropriately illustrated in the drawings referring
in this specification.
[0018] The fluid discharging apparatus 100 is a 3D printer which is a three-dimensional
modeling device. The fluid discharging apparatus 100 models a three-dimensional object
by discharging a fluid FL and piling a layer which has been obtained by curing the
fluid FL. In this specification, "discharge" means that a fluid is released outwardly
from a space in which the fluid is accommodated, by any force including gravity, and
has a concept of including "ejection" of releasing a fluid by pressure. A specific
example of a fluid FL which is discharged as a material of a three-dimensional object
as a modeling target by the fluid discharging apparatus 100 will be described later.
The fluid discharging apparatus 100 includes a discharging unit 10, a supply unit
30, a modeling stage 40, a moving mechanism 45, an energy applying unit 50, and a
control unit 60.
[0019] The discharging unit 10 corresponding to a head unit in a 3D printer and discharges
a fluid FL which is a material having fluidity, in a form of a fluid droplet. The
"fluid droplet" means a particulate lump of a fluid and means a liquid droplet in
a case where the fluid is a liquid. The shape of the fluid droplet is not limited.
The shape of the fluid droplet may be spherical or may be a shape in which a spherical
shape is extended in one direction, or a shape of, for example, a needle shape or
a rod shape. The number of discharged fluid droplets for one discharge is not limited
to 1 and a plurality of fluid droplets may be assumed to be discharged. The discharging
unit 10 includes an accommodation unit 11, a moving object 12, a driving mechanism
13, and a driving circuit 14.
[0020] The accommodation unit 11 is configured as a hollow container and accommodates a
fluid FL discharged by the discharging unit 10. In the reference example, the accommodation
unit 11 has a shape which is substantially cylindrical, and is configured of, for
example, stainless steel. A discharge port 15 which functions as a nozzle for discharging
the fluid FL is provided in the bottom surface 11b of the accommodation unit 11.
[0021] The discharge port 15 is provided as a through-hole which communicates with the internal
space of the accommodation unit 11 and has an opening section having a substantially
circle shape. In the reference example, the discharge port 15 is opened in the vertical
direction. An opening diameter of the discharge port 15 may be about 10 to 200 µm,
for example. The length of the discharge port 15 in the vertical direction may be
about 10 to 30 µm, for example.
[0022] The accommodation unit 11 includes a storage chamber 16, a pressure chamber 17, and
a driving chamber 18. The storage chamber 16 stores the fluid FL. The storage chamber
16 is connected to a flow passage 19 for receiving the fluid FL which is supplied
from the supply unit 30 by pressure. The flow passage 19 is configured as a pipeline
which penetrates an outer wall of the accommodation unit 11. A tapered portion in
which an inclined wall surface which is inclined downwardly toward the discharge port
15 has a diameter which is reduced downwardly is formed at a lower end of the storage
chamber 16. The tapered portion may be omitted and the bottom surface of the storage
chamber 16 may be configured by a substantially horizontal surface.
[0023] The pressure chamber 17 is positioned under the storage chamber 16. The pressure
chamber 17 spatially continues to the storage chamber 16 and is opened at the lower
end of the storage chamber 16. The discharge port 15 is opened at a lower end of the
pressure chamber 17. As will be described later, the pressure chamber 17 is spatially
separated from the storage chamber 16 by the moving object 12, when the moving object
12 is disposed at a closed position at which the discharge port 15 is closed. The
opening area of the pressure chamber 17 in a section which is perpendicular to an
opening direction of the discharge port 15 is greater than the opening area of the
discharge port 15, and flow path resistance of the pressure chamber 17 is smaller
than the flow path resistance of the discharge port 15.
[0024] The driving chamber 18 is positioned over the storage chamber 16 and accommodates
the driving mechanism 13. The driving chamber 18 is spatially separated from the storage
chamber 16 by a sealing member 21 which will be described later, such that the fluid
FL stored in the storage chamber 16 is not entered. Thus, the driving mechanism 13
is protected from the fluid FL.
[0025] The moving object 12 is accommodated in the accommodation unit 11. The moving object
12 is disposed over the discharge port 15. In the reference example, the moving object
12 is configured by a metal columnar member. The moving object 12 is disposed so as
to cause the central axis of the moving object 12 to coincide with the central axis
NX of the discharge port 15. The shape of the moving object 12 is not limited to the
columnar shape. The moving object 12 may have, for example, a substantially triangular
pyramid shape or a substantially spherical shape.
[0026] The moving object 12 is disposed over the storage chamber 16 and the driving chamber
18. The tip portion 12a of the moving object 12 is accommodated in the storage chamber
16. The rear end portion 12b of the moving object 12 is accommodated in the driving
chamber 18. In the reference example, the tip portion 12a of the moving object 12
has a hemispherical shape. The rear end portion 12b of the moving object 12 has a
substantially disc shape projected in a horizontal direction. The main body portion
12c of the moving object 12 between the tip portion 12a and the rear end portion 12b
has a substantially columnar shape. The diameter of the main body portion 12c may
be about 0.3 to 5 mm, for example.
[0027] An annular sealing member 21 which is configured by a resin O-ring is disposed at
a boundary between the storage chamber 16 and the driving chamber 18. The main body
portion 12c of the moving object 12 is inserted into a through-hole at the middle
of the sealing member 21. The outer circumferential surface of the sealing member
21 is air-tightly in contact with the inner wall surface of the accommodation unit
11. The inner circumferential surface of the sealing member 21 is air-tightly in contact
with the main body portion 12c of the moving object 12. Thus, the storage chamber
16 and the driving chamber 18 are spatially separated from each other, as described
above.
[0028] The moving object 12 is disposed in the accommodation unit 11, so as to be movable
in a first direction D1 toward the discharge port 15 and in a second direction D2
away from the discharge port 15. In the reference example, the first direction D1
and the second direction D2 together are parallel to the central axis of the moving
object 12 and are parallel to the vertical direction. In the reference example, the
moving object 12 moves back and forth in the vertical direction. The moving object
12 moves while rubbing the inner circumferential surface of the sealing member 21.
In the reference example, the moving object 12 moves in a range of about 10 to 500
µm.
[0029] When being positioned at the lowest side position, the tip portion 12a of the moving
object 12 comes into line-contact with the circumferential portion of an opening of
the pressure chamber 17 in the storage chamber 16. Thus, the discharge port 15 is
closed against the storage chamber 16 and a spatial connection between the storage
chamber 16 and the discharge port 15 is cut off. In this specification, the position
of the moving object 12 at this time is referred to as "a closed position".
[0030] The driving mechanism 13 applies a driving force for movement to the moving object
12. The driving mechanism 13 includes a piezoelectric element 23 and an elastic member
24. The piezoelectric element 23 has a configuration in which a plurality of piezoelectric
materials is stacked. The length of the piezoelectric element 23 is changed in a direction
in which the piezoelectric materials are stacked, in accordance with the level of
a voltage applied to the piezoelectric materials. A voltage is applied to the piezoelectric
element 23 from the driving circuit 14.
[0031] The upper end portion of the piezoelectric element 23 is fixed to an upper wall surface
of the driving chamber 18. The lower end portion of the piezoelectric element 23 is
in contact with the rear end portion 12b of the moving object 12. The piezoelectric
element 23 is stretched and a load is applied to the moving object 12, and thus the
moving object 12 moves in the first direction D1.
[0032] The elastic member 24 biases the moving object 12 in the second direction D2. In
the reference example, the elastic member 24 is configured by a disc spring. The elastic
member 24 is disposed on a lower side of the rear end portion 12b of the moving object
12, so as to surround the main body portion 12c. The elastic member 24 applies a force
to the rear end portion 12b in the second direction. The elastic member 24 may be
configured by a helical spring instead of the disc spring. When the piezoelectric
element 23 is contracted, the moving object 12 moves in the second direction D2 by
the force applied from the elastic member 24, so as to follow the lower end portion
of the piezoelectric element 23.
[0033] In the discharging unit 10, the moving object 12 moves to reciprocate, and thus fluid
droplets of the fluid FL are discharged from the discharge port 15. A discharging
mechanism of a fluid droplet in the discharging unit 10 will be described later. In
the discharging unit 10, a wall portion which constitutes the bottom surface 11b of
the accommodation unit 11 and in which the discharge port 15 is not provided may be
configured by a member which is detachable from the main body of the accommodation
unit 11. The above member is detached from the accommodation unit 11, and thus, for
example, cleaning or maintenance of the discharge port 15, replacement or the like
when deterioration or damage occurs is easily performed. In addition, replacement
with various discharge ports 15 having different opening diameters (nozzle diameters)
is possible. Further, in the discharging unit 10, each of the components such as the
moving object 12, the sealing member 21, and the elastic member 24, which are accommodated
in the accommodation unit 11 may be configured to be detachable from the accommodation
unit 11. Thus, maintenance of the discharging unit 10 or replacement of the component
is easily performed.
[0034] The supply unit 30 supplies the fluid FL to the storage chamber 16 of the accommodation
unit 11 through the flow passage 19 by pressure. The supply unit 30 includes piping
31, a fluid storage unit 32, and a pressure generation unit 33. The piping 31 connects
the flow passage 19 of the accommodation unit 11 and the fluid storage unit 32. The
fluid storage unit 32 is a supply source of the fluid FL in the fluid discharging
apparatus 100 and is configured by a tank for storing the fluid FL. In the fluid storage
unit 32, a solvent is mixed in the stored fluid FL, and thus viscosity of the fluid
FL is maintained to be predetermined viscosity. The viscosity of the fluid FL may
be about 50 to 40,000 mPa·s, for example.
[0035] The pressure generation unit 33 is configured by a pressing pump, for example. The
pressure generation unit 33 applies pressure for supplying the fluid FL in the fluid
storage unit 32 to the accommodation unit 11 through the piping 31 by pressure. The
pressure generation unit 33 applies pressure of, for example, about 0.4 to 0.6 MPa
to the fluid FL. In Fig. 1, the pressure generation unit 33 is provided on an upstream
side of the fluid storage unit 32. However, the pressure generation unit 33 may be
provided on a downstream side of the fluid storage unit 32.
[0036] The modeling stage 40 is disposed in the front of the opening direction of the discharge
port 15 in the discharging unit 10. The discharging unit 10 discharges the fluid FL
to the modeling stage 40 as a target object. A three-dimensional object is modeled
by fluid droplets of the fluid FL, which have been landed on the modeling stage 40.
In the reference example, the modeling stage 40 is configured by a member having a
flat plate shape, and is disposed substantially horizontally. The modeling stage 40
is disposed at a position which is separate vertically downwardly from the discharge
port 15 by about 1.5 to 3 mm, for example.
[0037] The moving mechanism 45 includes a motor or a roller, a shaft, and various actuators
which are used for displacing the modeling stage 40 with respect to the discharging
unit 10. The moving mechanism 45 displaces the modeling stage 40 relatively with respect
to the discharging unit 10 in the horizontal direction and in the vertical direction,
as represented by both the arrows X and Y in Fig. 1. Thus, the landed position of
the fluid FL on the modeling stage 40 is adjusted. The fluid discharging apparatus
100 may have a configuration in which the modeling stage 40 is fixed and the discharging
unit 10 is displaced with respect to the modeling stage 40.
[0038] The energy applying unit 50 applies energy to the fluid FL landed on the modeling
stage 40 so as to cure the fluid FL. In the reference example, the energy applying
unit 50 is configured by a laser device. The energy applying unit 50 applies light
energy to the fluid FL by irradiation with laser. The energy applying unit 50 includes
at least a laser light source, a condensing lens, and a galvano mirror (illustrations
thereof are omitted). The condensing lens condenses laser emitted from the laser light
source on the fluid FL landed on the modeling stage 40. The galvano mirror is used
for scanning with laser. The energy applying unit 50 scans a landed position of the
fluid droplet on the modeling stage 40 with laser and causes light energy of the laser
to sinter the powder material in the fluid FL. Alternatively, the powder material
in the fluid FL is melted and combined. Accordingly, a material layer constituting
a three-dimensional object is formed on the modeling stage 40.
[0039] The energy applying unit 50 may cure the fluid FL by a method other than laser irradiation.
The energy applying unit 50 may cure the fluid FL by irradiation with an ultraviolet
ray or may remove at least a portion of a solvent of the fluid FL by heating of a
heater and cure the powder material.
[0040] The control unit 60 is configured by a computer which includes a CPU 61 and a memory
62. The CPU 61 conducts various functions for controlling the fluid discharging apparatus
100 by reading and executing a computer program in the memory 62. The control unit
60 controls each of the discharging unit 10, the supply unit 30, the moving mechanism
45, and the energy applying unit 50 which have been described above, to perform modeling
processing for modeling a three-dimensional object.
[0041] The control unit 60 receives data MD for modeling a three-dimensional object from
an external computer (illustration thereof is omitted) which is connected to the fluid
discharging apparatus 100. Data representing each of material layers which are stacked
in a height direction of the three-dimensional object is included in the data MD.
The control unit 60 determines a timing of discharging fluid droplets of the fluid
FL to the discharging unit 10 or the size of the fluid droplet, based on the data
MD. The control unit 60 determines a landed position of the fluid droplet of the fluid
FL on the modeling stage 40, or a laser irradiation position and an irradiation timing
by the energy applying unit 50, based on the data MD. The three-dimensional object
modeled on the modeling stage 40 may be obtained through a sintering process in a
heating furnace, if necessary.
[0042] The control unit 60 transmits a driving signal to the driving circuit 14 in the modeling
processing, and thus controls moving of the moving object 12 and causes the fluid
FL to be discharged to the discharging unit 10 in the discharging unit 10. Control
of the moving object 12 by the control unit 60 at this time will be described later.
[0043] With the above configuration, the fluid discharging apparatus 100 in the reference
example, models a three-dimensional object which uses the fluid FL which is a discharging
target, as a material. Specific examples of the fluid FL which is the material of
the three-dimensional object will be described. In the reference example, the fluid
FL is a flowable composition which has a paste shape and includes a powder material
and a solvent. The fluid FL may include a powder material and a solvent. Examples
of the powder material may include single powder of magnesium (Mg), iron (Fe), cobalt
(Co), chrome (Cr), aluminium (Al), titanium (Ti), copper (Cu), and nickel (Ni), alloy
powder including one kind or more of the above metal (maraging steel, stainless steel,
cobalt chromium molybdenum, titanium alloy, nickel alloy, aluminum alloy, cobalt alloy,
and cobalt chromium alloy), and mixture powder obtained by mixing one or two kinds
or more selected from the single powder or alloy powder. Examples of the solvent of
the fluid FL may include water; (poly)alkylene glycol monoalkyl ethers such as ethylene
glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monomethyl
ether, and propylene glycol monoethyl ether; acetic acid esters such as ethyl acetate,
n-propyl acetate, iso-propyl acetate, n-butyl acetate, and iso-butyl acetate; aromatic
hydrocarbons such as benzene, toluene, and xylene; ketones such as methyl ethyl ketone,
acetone, methyl isobutyl ketone, ethyl-n-butyl ketone, diisopropyl ketone, and acetyl
acetone; alcohols such as ethanol, propanol, and butanol; tetraalkyl ammonium acetates;
sulfoxide solvents such as dimethyl sulfoxide and diethyl sulfoxide; pyridine solvents
such as pyridine, γ-picoline, and 2,6-lutidine; ionic liquids such as tetraalkyl ammonium
acetate (for example, tetrabutyl ammonium acetate); and mixtures of one or two kinds
or more selected from the above solvents.
[0044] The fluid FL may be a mixed material which is obtained by mixing a binder to the
powder material and the solvent and has a slurry shape or a paste shape. Examples
of the binder may include acrylic resin, epoxy resin, silicone resin, cellulose resin,
other synthetic resins, or PLA (polylactic acid), PA (polyamide), PPS (polyphenylene
sulfide), other thermoplastic resins. The fluid FL is not limited to a fluid including
the powder material. Examples of the fluid FL may include a fluid in which resin such
as general-purpose engineering plastics (for example, polyamide, polyacetal, polycarbonate,
modified polyphenylene ether, polybutylene terephthalate, and polyethylene terephthalate)
is melted. In addition, the fluid FL may be resin such as engineering plastics (for
example, polysulfone, polyethersulfone, polyphenylene sulfide, polyarylate, polyimide,
polyamide imide, polyether imide, and polyether etherketone). The fluid FL may include
metal other than the above-described metal, ceramics, resin, or the like. The fluid
FL may include a sintering aid.
[0045] The discharging process of the fluid FL in the fluid discharging apparatus 100 and
control of the moving object 12 by the control unit 60 in the discharging process
will be described with reference to Figs. 2 to 5B. Fig. 2 is a flowchart illustrating
a flow of the discharging process of the fluid FL. Fig. 3 is a diagram illustrating
an example of a graph representing a relationship between the position of the moving
object 12 and a time in the discharging process. The position of the moving object
12 in a vertical axis of the graph in Fig. 3 corresponds to the level of a voltage
applied to the piezoelectric element 23 by the driving circuit 14. Figs. 4A and 4B
are schematic diagrams illustrating details of the discharging processing performed
in the discharging process. Figs. 5A and 5B are schematic diagrams illustrating details
of the moving processing performed in the discharging process. Each of Figs. 4A, 4B,
5A, and 5B illustrates a form of a vicinity region of the discharge port 15 in the
accommodation unit 11.
[0046] The control unit 60 performs the following discharging process when a discharging
timing of the fluid FL by the discharging unit 10 is reached in the modeling processing.
If the discharging process which will be described below is performed one time, fluid
droplets of an amount as much as one dot are discharged. Firstly, the control unit
60 sequentially performs Process 1 and Process 2 as the discharging processing.
[0047] In Process 1, the control unit 60 controls the driving circuit 14 to apply a voltage
to the piezoelectric element 23 and thus causes the piezoelectric element 23 to be
contracted (time points t
1 to t
2 in Fig. 3). Thus, the moving object 12 moves from a closed position P
C at which the discharge port 15 is closed, in the second direction D2. The storage
chamber 16 and the pressure chamber 17 are in a state of communicating with each other,
and the discharge port 15 is opened (Fig. 4A). In Process 1, the moving object 12
reaches an open position P
O which is a position farthest from the discharge port 15 in a moving range of the
moving object 12. A moving period (time points t
1 to t
2) of the moving object 12 in the second direction in Process 1 may be about 50 to
400 µs, for example.
[0048] Then, the voltage applied to the piezoelectric element 23 is maintained during a
short waiting time (time points t
3 to t
4 in Fig. 3) which has been predetermined, and the moving object 12 is held at the
open position P
O. During the period, the fluid FL flows into a region between the tip portion 12a
of the moving object 12 and the discharge port 15 by using the pressure of the storage
chamber 16 as a driving force, and thus the fluid FL is replenished. The waiting time
at this time may be appropriately determined in accordance with the viscosity of the
fluid FL, pressure applied to the fluid FL by the pressure generation unit 33, the
volume of the storage chamber 16, and the like. The waiting time may be about 100
to 300 µs, for example.
[0049] In Process 2, the control unit 60 changes the voltage applied to the piezoelectric
element 23 by the driving circuit 14 so as to stretch the piezoelectric element 23
(time points t
3 to t
4 in Fig. 3). Thus, the moving object 12 moves in the first direction D1, the fluid
FL is extruded from the discharge port 15 and discharging the fluid FL is started
(Fig. 4B). In the reference example, in Process 2, the moving object 12 moves to the
closed position P
C. The tip portion 12a of the moving object 12 knocks on the inner wall surface of
the accommodation unit 11, and thus closes the discharge port 15. Thus, flowing of
the fluid FL into the pressure chamber 17 and the discharge port 15 can be temporarily
blocked. Accordingly, accuracy of adjusting the amount of the discharged fluid FL
is improved.
[0050] In Process 2, a speed at which the moving object 12 moves in the first direction
D1 may be the same as or greater than a speed at which the moving object 12 moves
in the second direction D2 in Process 1. In Process 2, a load applied to the moving
object 12 from the piezoelectric element 23 may be determined in accordance with aimed
pressure of the fluid FL at the discharge port 15 when the fluid FL is discharged
from the discharge port 15. For example, in a case where the aimed pressure is about
900 to 1100 MPa, the load applied to the moving object 12 by the piezoelectric element
23 may be about several hundred N.
[0051] After discharging the fluid FL from the discharge port 15 is started by Process 2,
the control unit 60 starts the moving processing during a period when the fluid FL
is discharged from the discharge port 15. The "period when the fluid FL is discharged
from the discharge port 15" means a period when a columnar fluid FL is suspended from
the discharge port 15 and does not include a period after the tip portion of the columnar
fluid FL is separated as a fluid droplet. That is, the period is a period after discharging
of the fluid FL from the discharge port 15 is started and before a fluid droplet of
the fluid FL is formed. This period varies depending on the viscosity of the fluid
FL, pressure of the fluid FL at the discharge port 15, or the like. The control unit
60 performs Process 2, and then starts the moving processing at an elapsed time point
which has been predetermined and at which it is expected that the fluid FL is in a
state of being discharged from the discharge port 15. For example, the control unit
60 may start the moving processing after a period of 0.001 to 0.04 s elapses from
when Process 2 is performed. The control unit 60 sequentially performs Process 3 and
Process 4 as the moving processing.
[0052] In Process 3, the control unit 60 controls the driving circuit 14 to apply a voltage
to the piezoelectric element 23 and thus causes the piezoelectric element 23 to be
contracted again (time points t
5 to t
6 in Fig. 3). Thus, moving of the moving object 12 in the second direction D2 is started
during the period when the fluid FL is discharged from the discharge port 15. In the
reference example, in Process 3, the moving object 12 moves to an intermediate position
P
M between the closed position P
C and the open position P
O (Fig. 5A).
[0053] The moving object 12 is moved in the second direction D2 in Process 3, and thus a
force from the discharge port 15 into the storage chamber 16 can be generated in the
fluid FL discharged from the discharge port 15. Thus, an inertial force and gravity
at a time of discharging act on a portion of the fluid FL on a lower end side thereof
which is suspended from the discharge port 15, and a force which draws the fluid FL
into the accommodation unit 11 acts on a portion of the fluid FL on an upper end side
thereof. Accordingly, moving of the moving object 12 in the second direction D2 causes
the tip portion of the fluid FL on the lower end thereof which is suspended from the
discharge port 15 to be separated as a fluid droplet and fly, as indicated by a broken
line. It can be interpreted that Process 3 is a process of moving the moving object
12 in the second direction D2 and separating a fluid droplet from a columnar fluid
FL. In addition, in Process 3, the moving object 12 moves in the second direction
D2, and thus an inertial force in a direction in which the fluid FL is drawn back
into the accommodation unit 11 is generated and an occurrence of a situation in which
the fluid FL remains at an outer portion of the discharge port 15 is suppressed. In
particular, in the reference example, the moving object 12 is moved from the closed
position P
C in the second direction D2, and thus the force which brings the fluid FL back into
the accommodation unit 11 is increased. Further, the occurrence of a situation in
which the fluid FL remains at an outer portion of the discharge port 15 is more suppressed.
[0054] In Process 3, as illustrated by a graph Ga of a two-dot chain line in Fig. 3, the
moving object 12 may be moved to the open position P
O. It is desirable that a moving distance of the moving object 12 in Process 3 is the
same as or smaller than a moving distance of the moving object 12 in Process 1 (time
points t
1 to t
2). Thus, an occurrence of a situation in which the moving distance of the moving object
12 is wastefully increased is suppressed and efficiency is increased. In particular,
if the moving distance of the moving object 12 in Process 3 is smaller than the moving
distance of the moving object 12 in Process 1, an occurrence of a situation in which
an outside air enters into the accommodation unit 11 from the discharge port 15 in
Process 3 is suppressed. It is desirable that a period (time points t
6 to t
8 in Fig. 3) until Process 4 is started after Process 3 is a period as short as the
large amount of the fluid FL does not flow into a region between the tip portion 12a
of the moving object 12 and the discharge port 15. It is desirable that the period
of time points t
6 to t
8 is at least a period shorter than the period of the time points t
2 to t
3. The period may be substantially omitted. Thus, an occurrence of a situation in which
the fluid FL is extruded from the discharge port 15 in Process 4 is suppressed.
[0055] In Process 4, the control unit 60 changes a voltage applied to the piezoelectric
element 23 by the driving circuit 14. Thus, the piezoelectric element 23 is stretched
and the moving object 12 is brought back to the closed position P
C (time points t
7 to t
8 in Fig. 3, Fig. 5B). Accordingly, a communication state between the discharge port
15 and the storage chamber 16 is cut off by the moving object 12 and an occurrence
of leakage of the fluid FL from the discharge port 15 is suppressed. It is desirable
that a speed when the moving object 12 is moved in the first direction D1 in Process
4 is slower than a speed when the moving object 12 is moved in the first direction
D1 in Process 2. Thus, an occurrence of a situation in which the fluid FL is discharged
from the discharge port 15 by moving the moving object 12 in Process 4 is suppressed.
It is possible to relieve an impact when the moving object 12 collides with the inner
wall surface of the accommodation unit 11 at the closed position P
C, and thus deterioration of the discharging unit 10 is suppressed.
[0056] As described above, according to the fluid discharging apparatus 100 and the method
of discharging the fluid FL in the discharging process thereof in the reference example,
the moving object 12 is moved in the second direction D2 during a period when the
fluid FL is discharged from the discharge port 15. Thus, separation of a fluid droplet
from a columnar fluid FL which is suspended from the discharge port 15 is accelerated.
An occurrence of a situation in which the fluid FL remains on the outside of the discharge
port 15 after the discharging process is suppressed. Thus, an occurrence of a situation
in which the redundant fluid FL is provided in the circumferential region of the discharge
port 15, which includes the discharge port 15, and thus discharging of the next fluid
FL is disturbed is suppressed. For example, an occurrence of a situation in which
there is a mistake in the amount of the discharged fluid FL in the next discharging
process or a situation in which a flying state of a fluid droplet of the fluid FL
discharged in the next discharging process is deteriorated is suppressed. Thus, it
is possible to smoothly and continuously perform discharging of a fluid droplet of
the fluid FL. Since an occurrence of a situation in which the redundant fluid FL adheres
to the circumferential region of the discharge port 15 is suppressed, it is possible
to reduce the number of times of performing cleaning processing of the circumferential
region of the discharge port 15, and efficiency is increased. Furthermore, according
to the fluid discharging apparatus 100 and the method of discharging the fluid FL
in the discharging process thereof in the reference example, it is possible to obtain
various advantages described in the above reference example.
B. Second Reference Example
[0057] Fig. 6 is a diagram illustrating a discharging process in a second reference example
of the invention. Fig. 6 is substantially the same as Fig. 3 having referred in the
first reference example except that the moving object 12 stops in a region between
the closed position P
C and an intermediate position P
M at the time points t
4 to t
5. A fluid discharging apparatus in the second reference example has a configuration
which is substantially the same as that of the fluid discharging apparatus 100 in
the first reference example (Fig. 1). A discharging process performed in the fluid
discharging apparatus in the second reference example is substantially the same as
the process described in the first reference example except for points which will
be described below.
[0058] In the discharging process in the second reference example, the control unit 60 causes
the moving object 12 not to reach the closed position P
C and but to stop at a return position P
N which is a position between the closed position P
C and the intermediate position P
M, in Process 2 of the discharging processing (time points t
4 to t
5). In Process 3 of the moving processing, the moving object 12 is moved from the return
position P
N, in the first direction D1. The return position P
N may be a position which is experimentally predetermined so as to cause the fluid
FL having a desired amount until the moving object 12 reaches the above position to
be discharged from the discharge port 15.
[0059] Even in a case of the fluid discharging apparatus and the method of discharging the
fluid FL in the discharging process in the second reference example, similarly to
those described in the first reference example, it is possible to suppress the occurrence
of a situation in which a redundant fluid FL is provided on the outside of the discharge
port 15, while a fluid droplet of the fluid FL is separated by the Process 3 of the
moving processing. According to the fluid discharging apparatus and the method of
discharging the fluid FL in the discharging process in the second reference example,
since the tip portion 12a of the moving object 12 does not collide with the inner
wall surface of the accommodation unit 11 in Process 2, it is possible to suppress
deterioration of the accommodation unit 11, which results from the collision. Further,
it is possible to reduce a moving distance of the moving object 12 in the discharging
process, and thus the discharging process is performed with high efficiency. Furthermore,
according to the fluid discharging apparatus and the method of discharging the fluid
FL in the discharging process in the second reference example, it is possible to exhibit
various advantages which are similar to those described in the first reference example.
C. Third Exemplary Embodiment
[0060] Fig. 7 is a diagram illustrating a discharging process in a third exemplary embodiment
of the invention. Fig. 7 illustrates an example of a graph representing the relationship
between the position of the moving object 12 and a time in the discharging process.
In the graph in Fig. 7, for convenience, only a period of time points t
4 to t
8 when Processes 3 and 4 of the moving processing are performed in the discharging
process is illustrated. In the third exemplary embodiment, a fluid discharging apparatus
has a configuration which is substantially the same as that of the fluid discharging
apparatus 100 in the first reference example (Fig. 1). The discharging process performed
in the fluid discharging apparatus in the third exemplary embodiment is substantially
the same as the process described in the first reference example except for points
which will be described below.
[0061] The discharging process in the third exemplary embodiment is substantially the same
as the discharging process in the first reference example except that the control
unit 60 changes the moving speed of the moving object 12 in Process 3. In the discharging
process in the third exemplary embodiment, the control unit 60 changes the moving
speed of the moving object 12 from a first speed v
1 which is an initial moving speed to a second speed v
2 which is slower than the first speed v
1, at a time point t
a in the middle of Process 3 of the moving processing. Since the speed of the moving
object 12 is high during a period of the time points t
5 to t
a, it is possible to quickly separate a fluid droplet from the fluid FL discharged
from the discharge port 15. Since the speed of the moving object 12 is low during
a period of the time points t
a to t
6, the occurrence of a situation in which an outside air is entered into the accommodation
unit 11 through the discharge port 15 is suppressed. In Process 3, the control unit
60 may gradually decrease the speed of the moving object 12 as illustrated by a graph
Gb of a two-dot chain line in Fig. 7. Thus, the control unit 60 may change the speed
of the moving object 12 from the first speed v
1 to the second speed v
2.
[0062] As described above, according to the fluid discharging apparatus and the method of
discharging the fluid FL in the discharging process in the third exemplary embodiment,
it is possible to suppress entering of an outside air into the accommodation unit
11 with improving separability of a fluid droplet, by controlling the speed of the
moving object 12 in Process 3. Furthermore, according to the fluid discharging apparatus
and the method of discharging the fluid FL in the discharging process in the third
exemplary embodiment, it is possible to exhibit various advantages which are similar
to those described in the first reference example.
D. Fourth Reference Example
[0063] Fig. 8 is a schematic diagram illustrating a configuration of a fluid discharging
apparatus 100A in a fourth reference example. For convenience, Fig. 8 illustrates
only some components of the fluid discharging apparatus 100A. The fluid discharging
apparatus 100A in the fourth reference example has a configuration which is substantially
the same as the configuration of the fluid discharging apparatus 100 in the first
reference example except that a fluid detection unit 70 is added. A discharging process
performed by the fluid discharging apparatus 100A in the fourth reference example
is substantially the same as that described in the first reference example except
that the moving speed or the moving distance of the moving object 12 is changed in
accordance with a detection result of the fluid detection unit 70, as will be described
below.
[0064] The fluid detection unit 70 detects a fluid FL adhering to the circumferential region
of the discharge port 15 on the outside of the accommodation unit 11, under the control
of the control unit 60. The circumferential region of the discharge port 15 includes
a region under the discharge port 15. The fluid detection unit 70 includes an imaging
device configured by a CCD image sensor or the like. The fluid detection unit 70 captures
an image of the circumferential region of the discharge port 15 during a period when
the discharging unit 10 does not discharge the fluid FL, and analyzes the captured
image. The thickness of a film of the fluid FL which is formed to cover the discharge
port 15 under the discharge port 15, or the area of an image of the film is detected
as a value indicating the amount of the fluid FL provided in the circumferential region
of the discharge port 15.
[0065] The control unit 60 changes at least one of a distance and a speed when the moving
object 12 moves in the second direction D2, in accordance with the amount of the fluid
FL detected by the fluid detection unit 70, in Process 3 of the next discharging process.
The control unit 60 changes the voltage which is applied to the piezoelectric element
23 by the driving circuit 14.
[0066] The control unit 60 may perform a control to cause the moving distance of the moving
object 12 to be increased as the amount of the fluid FL detected by the fluid detection
unit 70 becomes more. The control unit 60 may perform a control to cause the moving
speed of the moving object 12 to become faster as the amount of the fluid FL detected
by the fluid detection unit 70 becomes more. In the above controls, the control unit
60 may use a map or an expression which has been prepared in advance. The control
unit 60 may increase one or both of the moving distance and the moving speed of the
moving object 12 in comparison to a case where the detected amount of the fluid FL
is equal to or smaller than the threshold, when the amount of the fluid FL detected
by the fluid detection unit 70 is greater than a predetermined threshold.
[0067] If the moving distance or the moving speed of the moving object 12 in Process 3 is
set to be large, it is possible to increase a force which acts in a direction in which
the fluid FL discharged from the discharge port 15 is attracted into the accommodation
unit 11. Thus, for example, even though the fluid FL which is not attracted into the
accommodation unit 11 by the moving processing is provided during the continuous discharging
process of the fluid FL until now, it is possible to reduce such the remaining fluid
FL by the moving processing of the subsequent discharging process. A control in which
the moving distance of the moving object 12 in Process 3 is generally set to be short,
and thus entering of the outside air from the discharge port 15 is suppressed and
a control in which the moving distance of the moving object 12 is increased when the
remaining amount of the fluid FL accumulated in the circumferential region of the
discharge port 15 is high are possible.
[0068] As described above, according to the fluid discharging apparatus and the method of
discharging the fluid FL in the discharging process in the third exemplary embodiment,
it is possible to further suppress an occurrence of a situation in which the fluid
FL remains in the circumferential region of the discharge port 15. Furthermore, according
to the fluid discharging apparatus and the method of discharging the fluid FL in the
discharging process in the third exemplary embodiment, it is possible to exhibit various
advantages which are similar to those described in the first reference example.
E. Modification Examples
E1. Modification Example 1
[0069] In each of the examples, the discharging process is performed in the modeling processing
of modeling a three-dimensional object. On the other hand, the discharging process
may be performed at a time other than the time of the modeling processing. For example,
the discharging process may be performed during flushing which is performed for maintenance
of the discharging unit 10.
E2. Modification Example 2
[0070] In the examples, each of the first direction D1 and the second direction D2 which
are moving directions of the moving object 12 are directions parallel to a vertical
direction. On the other hands, each of the first direction D1 and the second direction
D2 may be not parallel to the vertical direction. The first direction D1 and the second
direction D2 may be inclined directions which intersect with the vertical direction.
In the examples, an opening direction of the discharge port 15 coincides with the
vertical direction. On the other hands, the opening direction of the discharge port
15 may not coincide with the vertical direction. For example, the opening direction
of the discharge port 15 may be a direction which intersects with the vertical direction
and is directed diagonally downwardly. E3. Modification Example 3
[0071] The configurations of the second reference example and the third exemplary embodiment
may be appropriately combined. For example, in Process 2 in the discharging process
of the third exemplary embodiment, the moving object 12 may not reach the closed position
P
C and but stop at the intermediate position P
M, as described in the second reference example.
E4. Modification Example 4
[0072] In the examples, the control unit 60 may set the speed when moving the moving object
12 to the closed position P
C, to be slower than the speed when moving the moving object 12 in the first direction
D1 in Process 2, in Process 4. On the other hands, the control unit 60 may set the
speed when moving the moving object 12 to the closed position P
C, to be equal to or faster than the speed when moving the moving object 12 in the
first direction D1 in Process 2, in Process 4.
E5. Modification Example 5
[0073] In each of the examples, the pressure chamber 17 of the accommodation unit 11 may
be omitted. In this case, the tip portion 12a of the moving object 12 at the closed
position P
C may come into contact with the inner circumferential portion of the discharge port
15 and may directly close the discharge port 15.
E6. Modification Example 6
[0074] In each of the examples, the moving object 12 is displaced with applying a load in
accordance with stretching or contracting of the piezoelectric element 23. On the
other hand, the moving object 12 may be displaced with applying a load by a method
other than the method using the piezoelectric element 23. For example, the moving
object 12 may be displaced with applying a load by pressure of a gas. In each of the
examples, the moving object 12 may be integrated with the piezoelectric element 23.
In addition, a configuration in which the tip portion of the piezoelectric element
23 moves to reciprocate in the accommodation unit 11, as the moving object 12 may
be made.
E7. Modification Example 7
[0075] In the fourth reference example, the fluid detection unit 70 detects the fluid FL
in the circumferential region of the discharge port 15 by an optical unit which uses
an imaging device. On the other hand, the fluid detection unit 70 may detect the fluid
FL in the circumferential region of the discharge port 15 by an optical unit other
than the imaging device. For example, the fluid detection unit 70 may detect that
the fluid FL having an amount which is equal to or greater than a predetermined amount
is provided in the circumferential region of the discharge port 15, by using a photo
sensor. The fluid detection unit 70 may detect the fluid FL in the circumferential
region of the discharge port 15 by a method other than the method using an optical
unit. In the fluid detection unit 70, an electrode may be provided in the circumferential
region of the discharge port 15, and the fluid FL provided in the circumferential
region of the discharge port 15 may be detected based on a change of resistance when
a current flows in the electrode.
E8. Modification Example 8
[0076] The fluid discharging apparatus in each of the examples, is realized as a three-dimensional
modeling device that models a three-dimensional object. On the other hand, the fluid
discharging apparatus may be not realized as the three-dimensional modeling device.
For example, the fluid discharging apparatus may be realized as an ink jet printer
that discharges an ink as the fluid or may be realized as a coating device that discharges
a coating material or a working device that discharges an adhesive having fluidity.
E9. Modification Example 9
[0077] In each of the examples, some or all of the function and the processing realized
by software may be realized by hardware. Some or all of the function and the processing
realized by hardware may be realized by software. Various circuits such as an integrated
circuit, a discrete circuit, or a circuit module obtained by combining the circuits
can be used as the hardware.